11 meeting of the International Argo Steering Team Scripps ...

measurements depend on knowing the precise timing of the Argo measurements, and this is
particularly true in the upper ocean, where temperature evolve rapidly. In addition science
questions focused on understanding rapidly evolving aspects of the ocean, such as the upper
ocean diurnal cycle, depend on knowing the precise timing of the Argo measurements. At
present, different manufacturers have adopted different conventions for defining the time when
Argo floats rise to the surface. Depending on the float type the best estimate of surfacing time
might come from the variable JULD, or the variable JULD_ASCENT_END, or an adjustment to
one of these assuming some knowledge of clock drift or time at surface. Brian King reports that
further information is available in raw transmission files that are not available to most Argo float
users.
Sarah Gille’s recommendations are to set standards for future Argo data reporting to make
surface arrival times easier to detect. This could include the following:
(1) Establish standard usage for the JULD and JULD_ASCENT_END variables for all
data centers.
(2) Have floats report their internal clock times when they (a) arrive at the surface, (b)
begin transmitting, and (c) at the moment of transmission, or else equivalent information
that would make it possible to have redundant information to determine profiling times.
(3) Include profile times in profile files (not just in trajectory files), with information
indicating whether estimated or exact (or with uncertainties.) If it is not possible to do
this, then establish consistent cycle numbering schemes for trajectory and profile files to
allow cross-comparison of data.
6.2 Status of Bio-Argo
Bio-optical and chemical sensors on profiling floats have been used for more than a decade.
They have matured a lot in terms of ease of integration and robustness with papers describing
them being published in high impact scientific journals. There are currently about 20 profiling
floats deployed and another 150 floats funded that include optical sensors (and about 200
others with oxygen and/or nitrate sensor). The International Ocean Color Coordinating Group
(IOCCG) has established a committee to provide recommendation on the best practices for the
use of optical sensors on profiling floats (Chair: H. Claustre). A white paper has been written
that will be shared with the greater community as soon as it is finalized later this year. In
addition much interest in these technologies has been generated in the OceanObs meeting in
Venice in 2009 and several manuscripts describing the promising future of these assets are in
press.
In order to establish a global observatory of profiling floats with biogeochemical sensors it is
imperative that actions be taken soon to standardize sensors, data streams and QC procedures
for both near-real-time and delayed mode. The IOCCG committee has tackled some of these
issues and more work is planed soon. Synergies with Argo are obvious and would benefit both
communities (increasing funding and user base). In order for this synergy to work, Argo will
need to be supplemented with additional personnel (to handle increased data complexity and
volume). Indeed, in France, efforts have been made to find additional funding for the Coriolis
data center to deal with the added work that will be caused from QC and dissemination of
biogeochemical data.
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